42. South Mountain Reservation

Interstate 78 crosses the southern end of the Watchung Mountains. West
of Newark, it passes through the Oranges, then passes through a gap in
the ridges of the 1st and 2nd Watchung Mountains. The Milburn Gap was
carved by an ancient river whose course was changed by the advance of
the Pleistocene glaciers. West of Milburn the interstate rises through
a series of road cuts carved through a thick section of the Preakness
Basalt of the 2nd Watchung. Once again, it is not safe or legal to stop
and examine cuts along the highway. Fortunately, there are numerous locations
to examine volcanic rocks and the intervening red beds in scenic settings
on public lands nearby, including the South Mountain Reservation and the
Watchung Reservation.

South Mountain Reservation is a 2,048 acre multiple use area (recreation,
watershed, and nature preserve) that encompasses a portion of 1st Watchung
Mountain in Milburn, New Jersey (Figure 96). The land encompasses the
traprock hillsides along the Rahway River. Washington's Rock, the hilltop
overlooking Milburn, was used as a lookout by Washington's Continental
Army to watch the movement of British troops in the Newark valley to the
east. At the time of the Revolution, most of the valley to the east of
the Watchung Mountains had been stripped of forests for use as lumber
and for agriculture, so that sentries had a good view from the top of
the 500 foot high ridge. The forests on the ridges were heavily lumbered
in the late 19th Century for firewood and paper making. At the turn of
the century, the Essex Count Park Commission organized the purchase of
the land. Restoration of the forests included the replanting of rhododendron
and mountain laurel groves in the 1910s, and the planting of red and white
pine by CCC projects in the 1930s. The park has an extensive system of
trails that wind along the Rahway River and along the hilltop of 1st Watchung
Mountain.

Figure 96. Map of South Mountain Reservation (1st Watchung) near
Milburn, New Jersey.

In terms of distance from Manhattan, this is one of the closest scenic
natural areas to the city. A hike on South Mountain in the late spring
or fall is highly recommended. The preserve is accessible via the Milburn
Station on the NJ Transit - Morris & Essex Lines from Penn Station
in Manhattan. The Locust Grove trailhead parking area is located just
across the road from the train station. By car, take I-78 west to Exit
49. Head east on Springfield Avenue about 1 mile and turn left on Milburn
Avenue. In about two miles turn right on Locust Grove. Go through the
underpass beneath the train. The trailhead parking area is in the wooded
area directly across the street. A suggested route is as follows (see
the trail on Figure 96). From the trailhead parking area, walk northward
along a gravel road, keeping the Rahway River on your left. Numerous paths
cross the road, but keep on the paths that follow the valley. You will
pass a couple ponds where the river has been dammed. About two miles into
the hike you will come to a path to scenic stone bridge across the stream.
Do not cross the bridge, but continue following the river trail northward
about a quarter mile. A trail to the right leads to Hemlock Falls, a falls
at the base of a long cascade that tumbles through a ravine carved in
the lower flow Orange Mountain Basalt (Figure 97). The trail to the top
of the falls leads to a expansive barren surface where the tops of columnar
joints in the basalt are well exposed. A large glacial erratic rests along
the stream just upstream from the lower falls (Figure 98). This is a very
scenic destination for a rest or a picnic! The return route involves walking
uphill along a wooded path on the south side of the falls. Follow any
of the broad paths southward up to the top of the ridge. All the trails
eventually intersects Crest Drive, a closed park road that runs along
the southeast side of the mountain. Walk south road to the overlooks on
the south end of South Mountain overlooking Milburn and the Newark Valley
beyond. The Manhattan skyline dominates the eastern horizon.

Figure 97. Hemlock Falls cascades off the columnar-jointed basalt
(Orange Mountain Basalt of the 1st Watchung) in the South Mountain
Reservation.

Figure 98. Columnar joints in the Orange Mountain Basalt just above
Hemlock Falls in the South Moutain Reservation. The large rounded
boulder to the right is a large glacial erratic.

South Orange Avenue leads eastward uphill through a pine forest planted
by the Civilian Concervation Corp, then crosses a foot bridge over the
road. The falls are a short walk down to the base of the hill. Like most
parks in New Jersey, deer are plentiful, so are the deer ticks that carry
lyme disease. Be sure to check for ticks after hiking.